A downhole tool for connecting an interior of a casing to a formation, the downhole tool including an inner housing extending along a longitudinal axis X; an outer housing that encloses the inner housing and forms first to fourth chambers; a first piston that separates the first and second chambers; a second piston that separates the third and fourth chambers; a port that is configured to fluidly communicate an outside and inside of the downhole tool; and a stopping mechanism that prevents the second piston from opening the port. The second piston is positioned to separate the port into an outer portion and an inner portion to interrupt a fluid communication between the outside and inside of the downhole tool.